Dinosaurs are vertebrate animals that range from reptile-like to bird-like.[1] Dinosaurs dominated the terrestrial ecosystem for over 160 million years, first appearing around 230 million years ago. 65 million years ago, at the end of the Cretaceous period, all non-avian dinosaurs became extinct. Dinosaurs still exist today in the line of birds (avian dinosaurs). Knowledge about dinosaurs is derived from both fossil and non-fossil records, includ ...

Including:

• Dinosaur - What is a dinosaur?
• Dinosaur - Definition
• Dinosaur - Size
• Dinosaur - Behavior
• Dinosaur - Study of dinosaurs
• Dinosaur - Classification
• Dinosaur - Order Saurischia
• Dinosaur - †Order Ornithischia
• Dinosaur - Evolution
• Dinosaur - Areas of debate
• Dinosaur - Warm-blooded?
• Dinosaur - Feathered dinosaurs and the bird connection
• Dinosaur - Evidence for Cenozoic dinosaurs
• Dinosaur - Bringing dinosaurs back to life
• Dinosaur - Discovery of probable soft tissue from dinosaur fossils
• Dinosaur - Extinction theories
• Dinosaur - Asteroid collision
• Dinosaur - The Oort cloud
• Dinosaur - Environment changes
• Dinosaur - History of discovery
• Dinosaur - In popular culture
• Dinosaur - Notes

Read more here: » Dinosaur: Encyclopedia - Dinosaur

See also:

Dinosaur, Dinosaur - What is a dinosaur?, Dinosaur - Definition, Dinosaur - Size, Dinosaur - Behavior, Dinosaur - Study of dinosaurs, Dinosaur - Classification, Dinosaur - Order Saurischia, Dinosaur - †Order Ornithischia, Dinosaur - Evolution, Dinosaur - Areas of debate, Dinosaur - Warm-blooded?, Dinosaur - Feathered dinosaurs and the bird connection, Dinosaur - Evidence for Cenozoic dinosaurs, Dinosaur - Bringing dinosaurs back to life, Dinosaur - Discovery of probable soft tissue from dinosaur fossils, Dinosaur - Extinction theories, Dinosaur - Asteroid collision, Dinosaur - The Oort cloud, Dinosaur - Environment changes, Dinosaur - History of discovery, Dinosaur - In popular culture, Dinosaur - Religious points of view, Dinosaur - Notes and references, Dinosaur - General references

Read more here: » Dinosaur: Encyclopedia II - Dinosaur - Areas of debate

Dinosaur - Definition. The superorder or clade "Dinosauria" was formally named by the English scientist Richard Owen in 1842. The term is a portmanteau derived from the Greek words deinos ("terrible" or "fearfully great" or "formidable") and sauros ("lizard" or "reptile"). Owen chose it to express his awe at the size and majesty of the extinct animals, not out of fear or trepidation at their size ...

See also:

Dinosaur, Dinosaur - What is a dinosaur?, Dinosaur - Definition, Dinosaur - Size, Dinosaur - Behavior, Dinosaur - Study of dinosaurs, Dinosaur - Classification, Dinosaur - Order Saurischia, Dinosaur - †Order Ornithischia, Dinosaur - Evolution, Dinosaur - Areas of debate, Dinosaur - Warm-blooded?, Dinosaur - Feathered dinosaurs and the bird connection, Dinosaur - Evidence for Cenozoic dinosaurs, Dinosaur - Bringing dinosaurs back to life, Dinosaur - Discovery of probable soft tissue from dinosaur fossils, Dinosaur - Extinction theories, Dinosaur - Asteroid collision, Dinosaur - The Oort cloud, Dinosaur - Environment changes, Dinosaur - History of discovery, Dinosaur - In popular culture, Dinosaur - Religious points of view, Dinosaur - Notes and references, Dinosaur - General references

Read more here: » Dinosaur: Encyclopedia II - Dinosaur - What is a dinosaur?

The Paleocene epoch (65-56 MYA) ("early dawn of the recent") is the first geologic epoch of the Palaeogene period in the modern Cenozoic era. As with most other older geologic periods, the strata that define the epoch's beginning and end are well identified, but the exact date of the end is uncertain. The Paleocene epoch immediately followed the mass extinction event at the end of the Cretaceous, known as the K-T boundary (Cretaceous - Tertiary), which marks the demise of the dinosaurs. The die-off of the dinosaurs left unfille ...

Including:

• Paleocene - Paleocene subdivisions
• Paleocene - Paleocene climate
• Paleocene - Paleocene paleogeography
• Paleocene - Paleocene flora
• Paleocene - Paleocene fauna
• Paleocene - Mammals
• Paleocene - Reptiles
• Paleocene - Birds
• Paleocene - Paleocene oceans

Read more here: » Paleocene: Encyclopedia - Paleocene

The Cretaceous-Tertiary (K-T or KT) extinction event, also known as the KT boundary, was a period of massive extinction of species, about 65.5 million years ago. It corresponds to the end of the Cretaceous Period and the beginning of the Tertiary Period. (K is the traditional abbreviation for the Cretaceous period. Cretaceous comes from the Latin for chalk, creta. The K comes from the German word for chalk kreide, or possibly Greek kreta. The K is used so as ...

Including:

• Cretaceous-Tertiary extinction event - Casualties of the extinction
• Cretaceous-Tertiary extinction event - Theories
• Cretaceous-Tertiary extinction event - Alvarez hypothesis
• Cretaceous-Tertiary extinction event - Chicxulub crater
• Cretaceous-Tertiary extinction event - Deccan traps
• Cretaceous-Tertiary extinction event - Multiple impact event
• Cretaceous-Tertiary extinction event - Supernova hypothesis
• Cretaceous-Tertiary extinction event - Further skepticism
• Cretaceous-Tertiary extinction event - Other mass extinctions

Read more here: » Cretaceous-Tertiary extinction event: Encyclopedia - Cretaceous-Tertiary extinction event

The mammals are the class of vertebrate animals characterized by the presence of mammary glands, which in females produce milk for the nourishment of young; the presence of hair or fur; and which have endothermic or "warm-blooded" bodies. The brain regulates endothermic and circulatory systems, including a four-chambered heart. Mammals encompass some 5500 species, distributed in about 1200 genera, 152 families and up to 46 orders, though this varies depending on the classification scheme adopted. Phylogenetically, MammaliaIncluding:

• Mammal - Characteristics
• Mammal - Origins
• Mammal - In the Mesozoic
• Mammal - In the Paleocene
• Mammal - Classification
• Mammal - Standardized textbook classification
• Mammal - McKenna/Bell classification
• Mammal - Molecular classification of placentals
• Mammal - Classification system used in related articles

Read more here: » Mammal: Encyclopedia - Mammal

Ammonites are an extinct group of marine animals (subclass Ammonoidea) in the phylum Mollusca and class Cephalopoda. Their closest living relative is probably not the modern Nautilus, whom they resemble, but rather the Subclass Coleoidea (octopus, squid, and cuttlefish). Their fossil shells take the form of flat spirals (though there are some rarer helically spiraled and non-spiraled forms, called heteromorphs) and are responsible for the animals' name as they somewhat resemble a tightly coiled ram's horn (the god Ammon was com ...

Including:

• Ammonite - Classification
• Ammonite - Life
• Ammonite - Shell anatomy and diversity
• Ammonite - Basic shell anatomy
• Ammonite - Sexual dimorphism
• Ammonite - Variations in shape
• Ammonite - The aptychus
• Ammonite - Size
• Ammonite - Ammonite distribution
• Ammonite - Trivia
• Ammonite - References and further reading

Read more here: » Ammonite: Encyclopedia - Ammonite

Skeptics remain. Although there is now general agreement that there was at least one huge impact at the end of the Cretaceous that led to the iridium enrichment of the K-T boundary layer, it is difficult to directly connect this to mass extinction, and in fact there is no clear linkage between an impact and any other incident of mass extinction, although research on other events also implicates impacts. One interesting note about the K-T event is that most of the larger animals that survived were to some degree aquatic, implying ...

See also:

Cretaceous-Tertiary extinction event, Cretaceous-Tertiary extinction event - Casualties of the extinction, Cretaceous-Tertiary extinction event - Theories, Cretaceous-Tertiary extinction event - Alvarez hypothesis, Cretaceous-Tertiary extinction event - Chicxulub crater, Cretaceous-Tertiary extinction event - Deccan traps, Cretaceous-Tertiary extinction event - Multiple impact event, Cretaceous-Tertiary extinction event - Supernova hypothesis, Cretaceous-Tertiary extinction event - Further skepticism, Cretaceous-Tertiary extinction event - Other mass extinctions

Read more here: » Cretaceous-Tertiary extinction event: Encyclopedia II - Cretaceous-Tertiary extinction event - Further skepticism

The second and third timelines are each subsections of their preceding timeline as indicated by asterisks. See also:

Geologic time scale, Geologic time scale - Terminology, Geologic time scale - History of the time scale, Geologic time scale - Table of geologic time, Geologic time scale - Graphical timelines, Geologic time scale - External link

Read more here: » Geologic time scale: Encyclopedia II - Geologic time scale - Graphical timelines

Mammals belong among the amniotes, and in particular to a group called the synapsids, distinguished by the shape of their skulls, in particular the presence of a single hole where jaw muscles attach, called temporal fenestra. In comparison, dinosaurs, birds, and most reptiles are diapsids, with two temporal fenestrae; and turtles, with no temporal fenestra, are anapsids. From synapsids came the first mammal precursors, therapsids, and more specifically the eucynodonts, 220 Ma (mega annum, million years ag ...

See also:

Mammal, Mammal - Characteristics, Mammal - Origins, Mammal - In the Mesozoic, Mammal - In the Paleocene, Mammal - Classification, Mammal - Standardized textbook classification, Mammal - McKenna/Bell classification, Mammal - Molecular classification of placentals, Mammal - Classification system used in related articles

Read more here: » Mammal: Encyclopedia II - Mammal - Origins

A wide range of organisms became extinct at the end of the Cretaceous period. The most conspicuous, of course, were the dinosaurs. While there is evidence that dinosaur diversity declined in the Late Cretaceous of North America, many species are known from the Hell Creek and Lance Formations of the Late Cretaceous. These include six or seven families of theropods and a similar number of ornithischians. Among the Dinosauria, the only survivors were the birds, but birds suffered heavy losses. A number of diverse groups became extinct, includin ...

See also:

Cretaceous-Tertiary extinction event, Cretaceous-Tertiary extinction event - Casualties of the extinction, Cretaceous-Tertiary extinction event - Theories, Cretaceous-Tertiary extinction event - Alvarez hypothesis, Cretaceous-Tertiary extinction event - Chicxulub crater, Cretaceous-Tertiary extinction event - Deccan traps, Cretaceous-Tertiary extinction event - Multiple impact event, Cretaceous-Tertiary extinction event - Supernova hypothesis, Cretaceous-Tertiary extinction event - Further skepticism, Cretaceous-Tertiary extinction event - Other mass extinctions

Read more here: » Cretaceous-Tertiary extinction event: Encyclopedia II - Cretaceous-Tertiary extinction event - Casualties of the extinction

Paleocene - Mammals. Mammals had first appeared in the Triassic, and developed alongside the dinosaurs, exploiting ecological niches untouched by the larger and more famous Mesozoic animals: in the insect-rich forest underbrush, and high up in the trees. These smaller mammals (as well as birds, reptiles, amphibians, and insects) survived the mass extinction at the end of the Cretaceous, which wiped out the dinosaurs, and mammals ...

See also:

Paleocene, Paleocene - Paleocene subdivisions, Paleocene - Paleocene climate, Paleocene - Paleocene paleogeography, Paleocene - Paleocene flora, Paleocene - Paleocene fauna, Paleocene - Mammals, Paleocene - Reptiles, Paleocene - Birds, Paleocene - Paleocene oceans

Read more here: » Paleocene: Encyclopedia II - Paleocene - Paleocene fauna

Paleocene - Mammals. Mammals had first appeared in the Triassic, and developed alongside the dinosaurs, exploiting ecological niches untouched by the larger and more famous Mesozoic animals: in the insect-rich forest underbrush, and high up in the trees. These smaller mammals (as well as birds, reptiles, amphibians, and insects) survived the mass extinction at the end of the Cretaceous, which wiped out the dinosaurs, and mammals ...

See also:

Paleocene, Paleocene - Paleocene subdivisions, Paleocene - Paleocene climate, Paleocene - Paleocene paleogeography, Paleocene - Paleocene flora, Paleocene - Paleocene fauna, Paleocene - Mammals, Paleocene - Reptiles, Paleocene - Birds, Paleocene - Paleocene oceans, Paleocene - Reference

Read more here: » Paleocene: Encyclopedia II - Paleocene - Paleocene fauna

The largest defined unit of time is the Eon. Eons are divided into Eras, which are in turn divided into Periods, Epochs and Stages. At the same time, paleontologists define a system of faunal stages, of varying lengths, based on changes in the observed fossil assemblages. In many cases, such faunal stages have been adopted in building the geologic nomenclature, though in general there are far more recogni ...

See also:

Geologic time scale, Geologic time scale - Terminology, Geologic time scale - History of the time scale, Geologic time scale - Table of geologic time, Geologic time scale - Graphical timelines, Geologic time scale - External link

Read more here: » Geologic time scale: Encyclopedia II - Geologic time scale - Terminology

Geology of the Zion and Kolob canyons area - Regional forces. Compression from subduction off the west coast affected the area to some degree in later Mesozoic time by causing folding and thrust faulting. Evidence for this period can be seen in the Taylor Creek area in the Kolob section of the park. Tensional forces forming the Basin and Range physiogeographic province to the west about 20 to 25 million years ago in Tertiary time created the two faults that bound the Markagunt Plateau (which underlies the park); the Savier Fault ...

See also:

Geology of the Zion and Kolob canyons area, Geology of the Zion and Kolob canyons area - The Grand Staircase and basement rocks, Geology of the Zion and Kolob canyons area - Deposition of sediments, Geology of the Zion and Kolob canyons area - Kaibab Formation Upper Permian, Geology of the Zion and Kolob canyons area - Moenkopi Formation Lower Triassic, Geology of the Zion and Kolob canyons area - Chinle Formation Upper Triassic, Geology of the Zion and Kolob canyons area - Moenave Formation Lower Jurassic, Geology of the Zion and Kolob canyons area - Kayenta Formation Lower Jurassic, Geology of the Zion and Kolob canyons area - Navajo Formation Lower to Mid Jurassic, Geology of the Zion and Kolob canyons area - Temple Cap Formation Middle Jurassic, Geology of the Zion and Kolob canyons area - Carmel Formation Middle Jurassic, Geology of the Zion and Kolob canyons area - Dakota Sandstone Lower Cretaceous, Geology of the Zion and Kolob canyons area - Tectonic activity and canyon formation, Geology of the Zion and Kolob canyons area - Regional forces, Geology of the Zion and Kolob canyons area - Volcanic activity, Geology of the Zion and Kolob canyons area - Erosion

Read more here: » Geology of the Zion and Kolob canyons area: Encyclopedia II - Geology of the Zion and Kolob canyons area - Tectonic activity and canyon formation

Geology of the Zion and Kolob canyons area - Kaibab Formation Upper Permian. In later Permian time, the Toroweap basin (see above) was invaded by the warm, shallow edge of the vast Permian Ocean in what local geologists call the Kaibab Sea. Starting 260 million years ago, the yellowish-gray limestone of the fossil-rich Kaibab Formation was laid down as a limy ooze in a tropical climate. During this time, sponges, such as Actinocoelia meandrina, proliferated, only to be buried in lime mud and their internal ...

See also:

Geology of the Zion and Kolob canyons area, Geology of the Zion and Kolob canyons area - The Grand Staircase and basement rocks, Geology of the Zion and Kolob canyons area - Deposition of sediments, Geology of the Zion and Kolob canyons area - Kaibab Formation Upper Permian, Geology of the Zion and Kolob canyons area - Moenkopi Formation Lower Triassic, Geology of the Zion and Kolob canyons area - Chinle Formation Upper Triassic, Geology of the Zion and Kolob canyons area - Moenave Formation Lower Jurassic, Geology of the Zion and Kolob canyons area - Kayenta Formation Lower Jurassic, Geology of the Zion and Kolob canyons area - Navajo Formation Lower to Mid Jurassic, Geology of the Zion and Kolob canyons area - Temple Cap Formation Middle Jurassic, Geology of the Zion and Kolob canyons area - Carmel Formation Middle Jurassic, Geology of the Zion and Kolob canyons area - Dakota Sandstone Lower Cretaceous, Geology of the Zion and Kolob canyons area - Tectonic activity and canyon formation, Geology of the Zion and Kolob canyons area - Regional forces, Geology of the Zion and Kolob canyons area - Volcanic activity, Geology of the Zion and Kolob canyons area - Erosion

Read more here: » Geology of the Zion and Kolob canyons area: Encyclopedia II - Geology of the Zion and Kolob canyons area - Deposition of sediments

Ammonite - Basic shell anatomy. The chambered part of the ammonite shell is called a phragmocone. The phragmocone contains a series of progressively larger chambers, called camerae (sing. camera) that are divided by thin walls called septa (sing. septum). Only the last and largest chamber, the body chamber, was occupied by the living animal at any given moment. As it grew, it adde ...

See also:

Ammonite, Ammonite - Classification, Ammonite - Life, Ammonite - Shell anatomy and diversity, Ammonite - Basic shell anatomy, Ammonite - Sexual dimorphism, Ammonite - Variations in shape, Ammonite - The aptychus, Ammonite - Size, Ammonite - Ammonite distribution, Ammonite - Trivia, Ammonite - References and further reading

Read more here: » Ammonite: Encyclopedia II - Ammonite - Shell anatomy and diversity

The principles underlying geologic time scales were laid down by Nicholas Steno in the late 17th century. Steno argued that rock layers (strata) are laid down in succession, and that each represents a "slice" of time. He also formulated the principle of superposition, which states that any given stratum is probably older than those above it and younger than those below it. Steno's principles were simple; applying them to real rocks proved complex. Over the course of the 18th century geologists came to realize that: 1) Sequences of strata wer ...

See also:

Geologic time scale, Geologic time scale - Terminology, Geologic time scale - History of the time scale, Geologic time scale - Table of geologic time, Geologic time scale - Graphical timelines, Geologic time scale - External link

Read more here: » Geologic time scale: Encyclopedia II - Geologic time scale - History of the time scale

Main article: Mammal classification George Gaylord Simpson's classic "Principles of Classification and a Classification of Mammals" (AMNH Bulletin v. 85, 1945) was the original source for the taxonomy listed here. Simpson laid out a systematics of mammal origins and relationships that was universally taught until the end of the 20th century. Since Simpson's 1945 classification, the paleontological record has been recalibrated, and the intervening years have seen much debate and progress concerning the theoretical underpi ...

See also:

Mammal, Mammal - Characteristics, Mammal - Origins, Mammal - In the Mesozoic, Mammal - In the Paleocene, Mammal - Classification, Mammal - Standardized textbook classification, Mammal - McKenna/Bell classification, Mammal - Molecular classification of placentals, Mammal - Classification system used in related articles

Read more here: » Mammal: Encyclopedia II - Mammal - Classification

Geology of the British Isles - Proterozoic Era. The Gneisses, the oldest rocks in Britain or Ireland, date from at least 2,700 Ma (Ma = millions of years ago) in the Archean period of this era, the Earth itself being only about 4,600 Ma old. They are found in the far north west of Scotland and in the Hebrides, with a few small outcrops elsewhere. Formed from rock originally deposited at the surface of the planet, the rocks were later buried d ...

See also:

Geology of the British Isles, Geology of the British Isles - Geological history, Geology of the British Isles - Proterozoic Era, Geology of the British Isles - Paleozoic Era, Geology of the British Isles - Mesozoic Era, Geology of the British Isles - Cenozoic Era, Geology of the British Isles - Geological features, Geology of the British Isles - Geological resources, Geology of the British Isles - Events, Geology of the British Isles - Institutions, Geology of the British Isles - People, Geology of the British Isles - Awards

Read more here: » Geology of the British Isles: Encyclopedia II - Geology of the British Isles - Geological history